Method and apparatus for digital encryption

• US 5,675,653 A
• Filed: 11/06/1995
• Issued: 10/07/1997
• Est. Priority Date: 11/06/1995
• Status: Expired due to Fees

• Current Assignee: Douglas Valmore Jr. Nelson
• Original Assignee: Douglas Valmore Jr. Nelson
• Inventors: Nelson, Douglas Valmore Jr.
• Primary Examiner(s): Cain, David C.
• Application Number:
  US08/553,955
• Time in Patent Office: 701 Days
• Field of Search: 380/29, 380/28, 380/49, 380/50, 380/21
• US Class Current: 380/28
• CPC Class Codes: H04L 9/0618 Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation

Abstract

The present invention is a real time digital encryption system which may be implemented in either hardware or software. The encryption system uses keys and an algorithm in which the encryption is determined in part by the data being encrypted, to obtain a scramble which is uniquely determined by the combination of the encryption keys and the data being encrypted, thereby making any effort at cryptanalysis extremely difficult, if not impossible. Consequently, anyone seeking to decrypt the data encrypted by the present invention would have to resort to an extensive brute force approach to such decryption efforts.

Claims

1. A cryptographic communications system comprising:

(a) a communications channel;

(b) an encoding means coupled to said channel and adapted for transforming a transmitted plaintext signal, b, to a ciphertext signal, c, and for transmitting c on said channel, said cryptographic communications system using at least a first key, J, having n bits and a second key, K, having n*(n-1)/2 bits, the bits of the K key being divided among n-1 K(i) keys, where i is a number which goes from 1 to n-1, and each K(i) key has i bits, and where J and K are used, in connection with the plaintext signal, b, to create a scramble of the original plaintext signal in accordance with the formula;

space="preserve" listing-type="equation">cb(i)=b(i)XOR(Boolean(cb.sub.(0→

i-1) ≧

K(i))XOR J(i),

where cb(i) is the output cipherbit, b(i) is the input plaintext bit, J(i) is a bit from a first encryption key, K(i) is a binary number comprised of i bits from said second encryption key, and the expression Boolean(cb.sub.(0→

i-1) ≧

K(i)) is 1 if the value of the preceding cipherbits, expressed as a single number is greater than or equal to the value of K(i), and the expression Boolean(cb.sub.(0→

i-1) ≧

K(i)) is 0 if the value of the preceding cipherbits, expressed as a single number is less than the value of K(i).

2. The cryptographic communications system of claim 1 further comprising an L key having one of two possible values, said two possible values of said L key being either 0 or 1, whereby when said L key has a first value, the bits of the ciphertext are rotated to the left, and when said L key has a second value, the bits of the ciphertext are rotated to the right.

3. A cryptographic communications system comprising:

(a) a communications channel;

(b) at least one encoding means adapted for transforming an input signal, b, to a ciphertext signal, c, each encoding means of said cryptographic communications system using at least a first key, J, having n bits and a second key, K, having n*(n-1)/2 bits, the bits of the K key being divided among n-1K(i) subkeys, where i is a number which goes from 1 to n-1, and each K(i) subkey has i bits, and where J and K are used, in connection with the input signal, b, to create a scramble of the original input signal in accordance with the formula;

space="preserve" listing-type="equation">cb(i)=b(i)XOR(Boolean(cb.sub.(0→

i-1) ≧

K(i))XOR J(i),

where cb(i) is the output cipherbit, b(i) is the input bit, J(i) is a bit from a first encryption key, K(i) is a binary number comprised of i bits from said second encryption key, and the expression Boolean(cb(₀→

i-1) ≧

K(i)) is 1 if the value of the preceding cipherbits, expressed as a single number is greater than or equal to the value of K(i), and the expression Boolean(cb.sub.(0→

i-1) ≧

K(i)) is 0 if the value of the preceding cipherbits, expressed as a single number is less than the value of K(i);

(c) means for receiving the output, c, of an encoding means, said means for receiving having an output which goes to a device selected from the group consisting of (i) an additional encoding means, and (ii) said communications channel,

whereby the output of each encoding means will become either the input of a subsequent encoding means, or the output onto said communications channel.

4. The communications system of claim 3 wherein there are m encoding means, m being a number greater than 0.

5. The communications system of claim 3 wherein each encoding means further comprises means for rotating the output of each said encoding means either left or right prior to passing said output on to said means for receiving.

6. The communications system of claim 5 wherein said means for rotating includes a fixed rotation of the bits of the output, c, whereby said bits will be rotated either to the left or to the right.

7. The communications system of claim 5 wherein said means for rotating is selectively determined by the setting of a bit in a rotation key, L, said rotation key having a single bit which designates whether the rotation should be to the left or to the right.

8. The communications system of claim 3 further comprising means for taking a master key having n bits and creating therefrom a set of keys, J(i) and K(i), wherein said keys J(i) and K(i) which are created from said master key are each comprised of bits which are from particular locations in said master key, whereby the selection of a single n-bit master key provides the bits which are mapped into the keys, J(i) and K(i).

9. A method for establishing cryptographic communications comprising the steps of:

(a) Selecting a first key, J, said first key capable of being expressed by n bits;

(b) Selecting a second key, K, having n*(n-1)/2 bits, said K key being comprised of n-1 K(i) subkeys, where i is a number which goes from 1 to n-1, and each K(i) subkey has i bits;

(c) Taking a plaintext message, b, and obtaining a ciphertext, cb, by repeatedly performing the following steps thereon;

(i) Breaking said plaintext message, b, into blocks, each block having no more than n bits;

(ii) Performing the bitwise operation;

space="preserve" listing-type="equation">cb(i)=b(i)XOR(Boolean(cb.sub.(0→

i-1) ≧

K(i))XOR J(i),

whereby, the ciphertext message cb(i) will be created in a bitwise manner.

10. The encryption method of claim 9 comprising the further step of selectively rotating the n bits of the ciphertext either to the right or to the left as determined by a rotation key, L., said rotation key, L, having one of two possible values, said two possible values of said L key being either 0 or 1, whereby when said L key has a first value, the bits of the ciphertext are rotated to the left, and when said L key has a second value, the bits of the ciphertext are rotated to the right.

11. The encryption method of claim 9 comprising the further step of processing the output ciphertext, cb, by at least one additional encryption step comprising performing the following steps thereon:

(i) Breaking said output ciphertext, cb, into blocks, each block having no more than n bits, each block being treated as "relative" plaintext, b;

(ii) Performing the bitwise operation;

space="preserve" listing-type="equation">cb(i)=b(i)XOR(Boolean(cb.sub.(0→

i-1) ≧

K(i))XOR J(i),

whereby, the ciphertext message cb(i) will be created in a bitwise manner.

12. The encryption method of claim 11 comprising the further step of selectively rotating the n bits of the output ciphertext either to the right or to the left as determined by a rotation key, L., said rotation key, L, having one of two possible values, said two possible values of said L key being either 0 or 1, whereby when said L key has a first value, the bits of the ciphertext are rotated to the left, and when said L key has a second value, the bits of the ciphertext are rotated to the right.

13. The encryption method of claim 10 further comprising the step of using a master key having n bits to create the keys J(i) and K(i), whereby the n bits of the master key are selectively distributed among the bits of the J(i) and K(i) keys.